#define _CRT_SECURE_NO_WARNINGS
#include<stdio.h>
int main()
{
	int arr[5] = { 0 };
	double average = 0.0, sum = 0.0;
	int i = 0;
	for (i = 0; i < 5; i++)
		scanf("%d", &arr[i]);
	for (i = 0; i < 5; i++)
		sum += arr[i];
	average = sum / 5.0;
	printf("%.1lf", average);
}